The disclosed invention is directed generally to a keyboard pushbutton switch, and more specifically is directed to a keyboard pushbutton switch having a long travel, and enhanced tactile and audible feedback, and improved contact reliability.
Pushbutton switches are utilized in keyboards for calculators, device control panels, and the like. A known pushbutton switch structure includes a dome-shaped metallic contact which contactively engages contacts on a printed circuit board when deformed by actuation of an associated keycap. The deformation of the metallic dome provides both tactile feedback and audible feedback.
An important consideration with a pushbutton switch having a metallic dome contact is the relatively small contact area provided by the deformed dome, which makes such switches susceptible to non-closure due to dust and dirt contamination. In order to increase reliability, some metallic dome pushbutton switches are individually packaged for insertion in printed circuit boards. Such switches can be more expensive and bulkier.
Another consideration with metallic dome pushbutton switches is transmission of the keypress force to the printed circuit board, which if excessive could cause damage.
A further consideration with pushbutton switches having metallic dome contacts is a limitation on the amount of key travel imposed by the metallic dome. Relatively longer key travel provides for a more comfortable keypress.